Restructure randomized test to be a bit clearer and test more stuff

crates/fs/src/fs.rs

@@ -635,6 +635,21 @@ impl FakeFs {
         }
     }
 
+    pub async fn paths(&self) -> Vec<PathBuf> {
+        let mut result = Vec::new();
+        let mut queue = collections::VecDeque::new();
+        queue.push_back((PathBuf::from("/"), self.state.lock().await.root.clone()));
+        while let Some((path, entry)) = queue.pop_front() {
+            if let FakeFsEntry::Dir { entries, .. } = &*entry.lock().await {
+                for (name, entry) in entries {
+                    queue.push_back((path.join(name), entry.clone()));
+                }
+            }
+            result.push(path);
+        }
+        result
+    }
+
     pub async fn directories(&self) -> Vec<PathBuf> {
         let mut result = Vec::new();
         let mut queue = collections::VecDeque::new();